A well-known consequence of this difference is that in a narrow tube the surface of the liquid - the so-called meniscus - stands higher at the circumference than at the centre in the case of water; with quicksilver it is just the reverse.

Having more precise information about wear and tear on this portion of the knee - a blend of fibrous tissue and cartilage called the meniscus - could lead to its use as a biomarker in predicting who is at risk for developing osteoarthritis, researchers say.